Liberia has begun treating Ebola patients with serum therapy - a treatment made from the blood of recovered survivors.

Doctors hope the experimental treatment could help combat the virus that has been sweeping West Africa and killing thousands of people.

Up to 13 December, 6,841 people had been reported as having died from the disease.

The total number of reported cases is more than 18,000.

If a person has successfully fought off the infection, it means their body has learned how to combat the virus and they will have antibodies in their blood that can attack Ebola.

Doctors can then take a sample of their blood and turn it into serum - by removing the red blood cells but keeping the important antibodies - which can be used to treat other patients.

Ebola patients treated in the UK and the US have already received this type of treatment.

Doctors in Liberia will monitor how safe and effective the serum treatment being given at the ELWA Hospital in Monrovia is.

A number of Liberian health care workers have been trained to give the therapy.

Dr David Hoover, the programme's director, said: "This will empower local health care systems to become more self-sufficient and better serve their patients during this current epidemic as well as in the future."

Scientists are also exploring other Ebola treatments.

Image copyrightNIH/SPL

The US, UK and Canada are testing different kinds of vaccine in controlled clinical trials.

The aim is to have 20,000 doses that could be used in West Africa by early next year.